AUGUSTA, Maine (AP) An Army reservist who shot and killed 18 people in Maine last year had evidence of traumatic brain injuries, according to a brain tissue analysis by researchers from Boston University.

There was degeneration in the nerve fibers that allow for communication between different areas of the brain, inflammation and small blood vessel injury, according to Dr. Ann McKee of Boston Universitys Chronic Traumatic Encephalopathy (CTE) Center. The analysis was released Wednesday by the family of reservist Robert Card.

Card had been an instructor at an Army hand grenade training range, where it is believed he was exposed to repeated low-level blasts. It is unknown if that caused Cards brain injury and what role brain injury played in Cards decline in mental health. McKee made no connection between the brain injury and Cards violent actions.